Definitions

High pressure regulator is a control valve that reduces the input pressure of a fluid to a desired value at its output. When the medium conditions (inlet pressure, medium flow) change, the regulator can still maintain a stable outlet pressure and flow within a certain range.

Major Components

• Loading  element : Used for the operator to set the outlet pressure of the regulator by applying a loading force. Mainly the handle, valve stem, range spring.
• Sensing element : By sensing the pressure changes in outlet chamber to balance the loading force and the outlet pressure, and physically connect the loading element and the control element. 
  Types: diaphragm (Figure ) or piston.
• Control element : Regulate the relatively high inlet pressure to low outlet pressure, and adjust the orifice size through the stroke of the poppet to maintain a stable output pressure. The control elements mainly include the seat, seat retainer, poppet and poppet spring.

Working Principle

High pressure gas flows through a small orifice into a large space, causing the pressure to reduce. Pressure regulator is about balance of forces. The equation goes as follows:
F loading element= F sensing element + F control element
Wherein:
F loading element= Diaphragm spring force (F1)
F sensing element = Outlet pressure × diaphragm area(F2)
F control element= Inlet pressure× Poppet area (F3)+ Poppet spring force (F4)

Supply Pressure Effect
Based on the balance of force :
F1=F2+F3+F4
Wherein:
F1=Diaphragm spring force
F2=Outlet pressure
F3=Inlet pressure
F4=Poppet spring force
F1 and F4 is relatively constant. The inlet pressure decrease as cylinder is depleted, namely F3 reduces. The spring compression forces the lift poppet downwards, allowing more gas and pressure to build in the outlet chamber.